People with Social Anxiety Disorder (SAD) are at high risk for problematic alcohol use. Compared to people without SAD, people with SAD are between two and three times more likely to develop an Alcohol Use Disorder (AUD). SAD and alcohol problems each contribute dramatically to psychologically impairment and economic costs, but together, the co-occurrence of SAD and AUD is associated with greater impairment than either condition alone. This highly comorbid relationship has been studied broadly, but there is substantially less research on the etiology and maintenance factors that help explain the link between SAD and alcohol use. Of the research available, methodologies have been almost exclusively limited to global questionnaires and laboratory experiments that offer little information about daily patterns of antecedents and consequences of alcohol use. Surprisingly, no study to date has examined daily processes related to alcohol use for people with SAD. The proposed investigation aims to fill this gap. The overarching aim of this study is to illuminate temporal sequences of alcohol use and how particular contextual features moderate the relationship between alcohol use and social anxiety. This objective addresses NIAAA's mission of promoting research on the causes and consequences of alcoholism and alcohol-related problems and devising effective methods to do so. Specific aims of the study are fourfold. First, we will conduct the first daily diary investigation of drinking motives for people with SAD and collect identical data from healthy adults. Data generated from this study will offer a descriptive picture of daily alcohol use (including level of alcohol consumption, frequency and degree of motivations to drink) and allow for important comparisons between people with and without SAD. Second, we will evaluate how the presence of SAD alters the relationship between drinking motives and alcohol consumption and severity of drinking-related problems per drinking episode. Third, we will evaluate how motives for people with SAD differ across social situations. Based on prior research indicating that certain circumstances of social situations affect how people with SAD function, we want to test how naturally occurring social situations influence motivations to consume alcohol. Fourth, as an exploratory aim, we will evaluate how daily SAD symptoms predict daily drinking motives among people with SAD to address mixed findings explaining the SAD-AUD link. Information generated from this study has the potential to contribute substantially to theory and treatment development for SAD, AUDs, and their co-occurrence. The goals of the proposed study will be accomplished within a training plan aimed at developing expertise in alcohol use, SAD, and advanced research methodology. The training plan includes completion of relevant courses, individual supervision and mentorship by experts in the field, attendance at relevant workshops, and scientific writing and dissemination experience.